Transmit beamforming, which may improve wireless communications, requires the feedback of beamforming matrixes in a frequency division duplexing (FDD) mode. The feedback can be differential with respect to the previous feedback. Differential feedback exploits the correlation between the ideal beamforming matrixes across time in order to reduce feedback overhead and increase beamforming accuracy. A quantization codebook may be used to quantize the differential matrix for the feedback. Previously, quantization codebook is constant across time. This is not optimal.
Thus, a strong need exists for improvements in providing differential feedback used in transmit beamforming.
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